Good quality, made by European filter company. Foam power RAM sponge remote air filter, 43-45mm internal diameter, straight connection. 
 
Comes with jubilee clip. Works well with standard Lambretta air bellow (not supplied), but you need a tube to connect the two - We use a small piece of soil pipe.
 
Please check this fits your carb before buying.
 
Part number: LUHL2